Upright vacuum cleaners are a particularly popular type of vacuum cleaner for household and light industrial vacuum cleaning of floors and floor carpeting. Typically, the unit includes a cleaner head assembly mounted on wheels and having a suction generator driven by a motor, with the motor also providing a belt drive for the roller-type agitator or roller brush mounted on the chassis. The unit also includes an operating handle pivoted to the chassis which can be placed in a lower inclined position to assist the operator in moving the vacuum cleaner over the carpet and in an upright position whereby the vacuum cleaner can be conveniently stored in a closet or the like thereby occupying minimal space. A filter bag is generally mounted on the handle within a hard case or a flexible fabric bag with the filter bag communicating with a passageway at the positive pressure end of the suction generator or fan assembly to collect the dirt-laden air brought up from the floor or carpet. The handle may also carry a storage rack for the electric cord providing power from a wall outlet to the suction generating motor means.
In upright vacuum cleaners utilizing a flexible fabric bag housing for enclosing the filter bag, it is most common to fix the bottom of the fabric housing to the lower end of the handle or chassis and suspend the top of the bag from a coil spring which will maintain tension on the bag and hold it in the upright position. The bag includes a zipper running its length to provide access within the bag housing for installing and withdrawing a filter bag. The filter bag is arranged with the inlet port secured to the chassis at the discharge end of the suction generator or fan such that the opposite end of the bag is elevated and the dirt-laden air. As a result, the dirt-laden air being discharged into the bag will fill the bag from the bottom up and require passing the discharge air through the dirt collected at the bottom of the bag. This can create a fair amount of back pressure in the vacuum cleaner and result in frequently having to replace the filter bag in order to maintain the vacuum cleaning efficiency of the vacuum cleaner.
More recently, upright vacuum cleaners have been designed to provide an air discharge duct extending lengthwise up the handle from the discharge end of the suction generating fan within the chassis and discharging the air at the upper end of the handle. With such an arrangement, the bag is suspended from a filter bag holding bracket positioned at the discharge end of the duct so that the bag hangs with its inlet port at the top of the bag and the dirt-laden air is blown from the top to the bottom of the bag where the dirt collects as the discharge air passes through the air permeable filter bag. This type of vacuum cleaning unit has been available with a soft bag housing, as described above, and, alternatively, with a "hard case", namely an all plastic housing of generally rigid construction in the shape of an elongate box.
With the hard case design, a front cover plate is provided, also of plastic construction, which may be hinged at the bottom and provided with a retainer clip for closing the top end of the front panel. The overall appearance is quite streamlined, thus being aesthetically pleasing to the user. Also, due to its rigidity, the filter bag within its closure remains virtually undisturbed.
Nevertheless, the flexible fabric bag housing offers certain advantageous design features over that of the hard case, including light weight, ease of use, savings in material cost, and aesthetic design alternatives.